A good place to start would be reading Cliff Coe's book,44 Years Behind the Bow.It has some pretty good information from Cliff himself.Coe Archery was located in Otter Lake,Michigan for many years.I believe Cliff's bows with brush nocks were made in the 1940's.He was a great guy and one of the few legends of modern archery's innovators that I was fortunate enough to have met.